A one-component silicone-modified temperature-resistant epoxy structural adhesive composition and a preparation method thereof

Abstract

The application belongs to the technical field of epoxy structural adhesive and discloses a single-component organic silicon modified temperature-resistant epoxy structural adhesive composition and a preparation method thereof, the single-component organic silicon modified temperature-resistant epoxy structural adhesive composition comprises, in terms of weight percentage, 40-75 parts of epoxy resin, 26-47 parts of epoxy modified silicon oil, 21-28 parts of methyl phenyl silicon resin containing an alkoxy functional group, 6-8 parts of a curing agent, 24-40 parts of amino phenyl silicon oil, 0-18 parts of a defoaming agent and 1-3 parts of a leveling agent, the side chain or end chain of the epoxy modified silicon oil contains at least one epoxy group, the amino equivalent of the amino phenyl silicon oil is 670-3750 g / eq, and the phenyl content is 0.10-0.40 mol / 100g. The application provides a single-component organic silicon modified temperature-resistant epoxy structural adhesive composition, the epoxy modified silicon oil and the amino phenyl silicon oil can produce a synergistic effect, the high-temperature resistance of the composition is improved, and thus the problems such as the decrease of adhesion, the failure of insulation performance after 90-degree bending and the decrease of tensile strength of the epoxy structural adhesive composition in an environment exceeding 100 DEG C can be avoided.

Description

Technical Field

[0001] This application relates to the field of epoxy structural adhesive technology, specifically to a one-component organosilicon-modified high-temperature resistant epoxy structural adhesive composition and its preparation method. Background Technology

[0002] Epoxy structural adhesives are a class of adhesives that use one or more epoxy resins as the main component, with the addition of crosslinking agents, leveling agents, toughening agents, and other components. They are cured at high temperatures to achieve bonding between the surfaces of the same or different materials. These adhesives have high bonding strength, low curing shrinkage, and high mechanical strength after curing. During operation, they exhibit high compressive strength, high shear strength, and high adhesive strength, and can withstand high stress and high-intensity friction. Epoxy structural adhesives can be used to bond and support structures made of metal, ceramics, plastics, rubber, wood, etc., and under certain conditions, can directly replace traditional connection methods such as welding, riveting, and bolting.

[0003] Epoxy structural adhesives include one-component and two-component systems. One-component epoxy structural adhesives exhibit significant advantages in terms of ease of handling, long service life, environmental friendliness, economy, simplified processing, and automation adaptability. However, due to the need for product storage stability and ease of use, one-component epoxy structural adhesives have a lower degree of cross-linking compared to two-component systems. This results in lower bonding performance and poorer flexibility, making them unsuitable for small-size flexible bonding.

[0004] Existing technologies introduce polysiloxane chains into epoxy structural adhesive formulations to form organosilicon-epoxy composite systems. The high-temperature resistance and flexibility of polysiloxane chains compensate for the poor elongation at break and poor temperature resistance of epoxy resins, which is expected to further expand the application range of epoxy structural adhesives. However, since the crosslinking network of the adhesive formed by the organosilicon-epoxy composite system is still dominated by carbon networks, and the organosilicon network is short-chain and accounts for a small proportion, the crosslinking network of the structural adhesive is prone to breakage in high-temperature environments exceeding 100°C, and the adhesion will also decrease.

[0005] Therefore, it is necessary to develop an epoxy structural adhesive composition that can further improve the problem of structural adhesives weakening in high-temperature environments. Summary of the Invention

[0006] One of the objectives of this application is to provide a single-component silicone-modified high-temperature resistant epoxy structural adhesive composition that can maintain good performance in high-temperature environments exceeding 100°C, thereby improving the applicability of epoxy structural adhesives.

[0007] Another objective of this application is to provide a method for preparing a one-component organosilicon-modified high-temperature resistant epoxy structural adhesive composition, which can produce an epoxy structural adhesive with good overall performance.

[0008] Meanwhile, this application also provides a one-component organosilicon-modified high-temperature resistant epoxy structural adhesive composition, which, by weight, comprises: 40-75 parts epoxy resin, 26-47 parts epoxy-modified silicone oil, 21-28 parts methylphenyl silicone resin containing alkoxy functional groups, 6-8 parts curing agent, 24-40 parts aminophenyl silicone oil, 0-18 parts defoamer, and 1-3 parts leveling agent;

[0009] The side chain or end chain of the epoxy-modified silicone oil contains at least one epoxy group;

[0010] The aminophenyl silicone oil has an amino equivalent of 670-3750 g / eq and a phenyl content of 0.10-0.40 mol / 100g.

[0011] The technical solution of this application has at least the following advantages through the addition of epoxy-modified silicone oil and aminophenyl silicone oil:

[0012] (1) This application introduces long-chain polysiloxane structures such as epoxy-modified silicone oil to improve the bending resistance of structural adhesive under large-angle bending (±90°) conditions, with no cracking at the bending point and the insulation of the adhesive remaining intact.

[0013] (2) This application expands the high and low temperature working range of structural adhesives by introducing aminophenyl silicone oil as a temperature resistance enhancer;

[0014] (3) By combining epoxy modified silicone oil and aminophenyl silicone oil, this application can effectively maintain the comprehensive performance of epoxy structural adhesive under high and low temperature environments.

[0015] Preferably, the epoxy resin comprises 20-35 parts of phenolic epoxy resin and 20-25 parts of bisphenol F type epoxy resin; the epoxy equivalent of the phenolic epoxy resin should be between 92-110 g / eq, and the epoxy equivalent of the bisphenol F type resin should be between 160-500 g / eq.

[0016] Preferably, the epoxy group of the epoxy-modified silicone oil is at least one selected from glycidyl ether, epoxycyclohexyl, oxetyl, and tetrahydrofuran.

[0017] Preferably, the alkoxy-containing functional group includes at least one selected from methoxy, ethoxy, propoxy, and isopropoxy.

[0018] Furthermore, the alkoxy-containing functional group is directly connected to silicon atoms to form a Si-R structure, where R is an alkoxy-containing functional group.

[0019] Preferably, the curing agent is at least one selected from divinyltriamine, dicyandiamide, diaminodiphenylmethane, adipic acid dihydrazide, m-phenylenediamine, m-phenylenediamine, and isophorone diamine.

[0020] This application also provides a method for preparing a one-component organosilicon-modified heat-resistant epoxy structural adhesive composition, comprising the following steps:

[0021] Step 1: Mix epoxy resin, epoxy modified silicone oil, methyl phenyl silicone resin containing alkoxy functional groups and amino phenyl silicone oil evenly to obtain a mixture;

[0022] Step 2: Add curing agent, defoamer and leveling agent to the mixture and disperse to obtain a dispersion;

[0023] Step 3: Vacuum degassing at 25℃ and -0.1MPa for 15-30 min to obtain the composition.

[0024] Furthermore, the mixing method in step 1 is specifically: high-speed stirring and mixing at 25℃ and 1200-1500 rpm for 20-25 min; the dispersion method in step 2 is specifically: high-speed dispersion at 25℃ and 2500 rpm for 30-40 min.

[0025] Preferably, the single-component silicone-modified high-temperature resistant epoxy structural adhesive composition further includes thermally conductive powder, the content of which is 40-45 wt%.

[0026] In a further preferred embodiment of the present application, the single-component silicone-modified heat-resistant epoxy structural adhesive composition comprises the following steps:

[0027] Step 1: Mix epoxy resin, epoxy modified silicone oil, methyl phenyl silicone resin containing alkoxy functional groups and amino phenyl silicone oil evenly to obtain a mixture;

[0028] Step 2: Add curing agent, defoamer, thermally conductive powder and leveling agent to the mixture and disperse to obtain a dispersion;

[0029] Step 3: Vacuum degassing at 25℃ and -0.1MPa for 15-30 min to obtain the composition.

[0030] Furthermore, the mixing method in step 1 is specifically: high-speed stirring and mixing at 25℃ and 1200-1500 rpm for 20-25 min; the dispersion method in step 2 is specifically: high-speed dispersion at 25℃ and 2500 rpm for 30-40 min.

[0031] In practical applications, the single-component silicone-modified high-temperature resistant epoxy structural adhesive composition described in this application has a curing temperature of 180-200℃ and a curing time of 15-30 minutes.

[0032] Beneficial effects

[0033] Compared with the prior art, this application provides a single-component silicone-modified high-temperature resistant epoxy structural adhesive composition. The epoxy-modified silicone oil and aminophenyl silicone oil can produce a synergistic effect to improve the high-temperature resistance of the composition, thereby avoiding problems such as decreased adhesion, insulation failure after bending 90°, and decreased pull-out strength in epoxy structural adhesive compositions at temperatures exceeding 100°. Detailed Implementation

[0034] The present application will be further described below with reference to embodiments, but this does not constitute any limitation on the present application. Any limited modifications made within the scope of the claims of the present application shall still be within the scope of the claims of the present application.

[0035] To illustrate the technical content of this application in detail, the following description is provided in conjunction with the embodiments.

[0036] In the following examples and comparative examples, the epoxy equivalent of the phenolic epoxy resin was 106 g / eq, purchased from Huntsman Araldite phenolic epoxy 0510; the epoxy equivalent of the bisphenol F type epoxy resin was 170 g / eq, purchased from Nan Ya Plastics Co., Ltd. (Taiwan); NPEF-170; the alkoxy-containing methylphenyl silicone resin was purchased from Shenzhen Jipeng Silicon Fluorine Materials Co., Ltd. (SH-3047); dicyandiamide and m-phenylenediamine were both purchased from Shenzhen Huiya New Materials Technology Co., Ltd.; spherical alumina was purchased from Shenzhen Huiya New Materials Technology Co., Ltd.; the silicone defoamer was purchased from BYK-A530; and the silicone leveling agent was purchased from BYK-333.

[0037] The epoxy-modified silicone oil was prepared in-house using the following method: 172.3 parts of γ-(2,3-epoxypropoxy)propylmethyldimethoxysilane, 0.36 parts of hexamethyldisiloxane, 113.54 parts of dimethyldiethoxysilane, 5.72 parts of concentrated hydrochloric acid, and 44.61 parts of deionized water were mixed at room temperature and reacted at 75°C for 3 hours. Then, the mixture was distilled under reduced pressure at 95°C and -0.1 MPa until transparent. Subsequently, the lower oily liquid was extracted twice using a sodium carbonate saturated ethanol solution. The extract was then rotary evaporated at 95°C to obtain the epoxy-modified silicone oil. The epoxy content of the epoxy-modified silicone oil was 0.28 mol / 100g.

[0038] The aminophenyl silicone oil was prepared in-house using the following method: 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane (19.88 parts, 0.080 mol), octamethylcyclotetrasiloxane (111.97 parts), a mixed cyclic form of methylphenylsiloxane (68.15 parts), and tetramethylammonium hydroxide pentahydrate (1.60 parts) were added to a straight four-necked flask equipped with a thermometer, condenser, and constant pressure funnel. The mixture was kept at 90°C for 1 h under nitrogen atmosphere; the temperature was then increased to 95°C and refluxed for 4 h; the reflux condenser was removed and the container was opened, and the mixture was heated to 145°C and stirred for 1.5 h; after cooling to room temperature, the mixture was filtered to remove scum and precipitate; then, the liquid was rotary evaporated at 150°C and -0.95 MPa to remove low-boiling-point substances to obtain the aminophenyl silicone oil, with an amino equivalent of 1394 g / eq and a phenyl content of 0.28%. mol / 100g.

[0039] All the portions mentioned above are by weight.

[0040] Example 1

[0041] A one-component silicone-modified heat-resistant epoxy structural adhesive composition is prepared by the following steps:

[0042] Step 1: Mix 35.0g of phenolic epoxy resin, 20.4g of bisphenol F type epoxy resin, 46.7g of epoxy modified silicone oil, 28.0g of alkoxy-containing methyl phenyl silicone resin and 24.1g of amino phenyl silicone oil according to the weight parts, and stir at high speed at 25℃ and 1500rpm for 25min.

[0043] Step 2: Add 8.00 g of dicyandiamide, 65.0 g of spherical alumina, 3.3 g of silicone defoamer and 3.3 g of silicone leveling agent to the mixed components, and disperse at high speed at 25℃ and 2500 rpm for 40 min.

[0044] Step 3: Vacuum degassing at 25℃ and -0.1MPa for 20 minutes.

[0045] Example 2

[0046] A one-component silicone-modified heat-resistant epoxy structural adhesive composition is prepared by the following steps:

[0047] Step 1: Mix the 20.0g phenolic epoxy resin, 20.4g bisphenol F type epoxy resin, 46.7g epoxy modified silicone oil, 28.0g methyl phenyl silicone resin containing alkoxy functional groups, and 24.1g amino phenyl silicone oil, and stir at high speed at 25°C and 1200rpm for 20min.

[0048] Step 2: Add 8.0g of dicyandiamide, 73.0g of spherical alumina, 3.2g of silicone defoamer and 3.2g of silicone leveling agent to the mixed components, and disperse at high speed for 30 min at 25℃ and 2500rpm.

[0049] Step 3: Vacuum degassing at 25℃ and -0.1MPa for 25 minutes.

[0050] Example 3

[0051] A one-component silicone-modified heat-resistant epoxy structural adhesive composition is prepared by the following steps:

[0052] Step 1: Mix the 21.0g phenolic epoxy resin, 25.0g bisphenol F type epoxy resin, 26.9g epoxy modified silicone oil, 21.3g methyl phenyl silicone resin containing alkoxy functional groups, and 24.1g amino phenyl silicone oil according to the weight parts, and stir at high speed at 25℃ and 1400rpm for 23 min.

[0053] Step 2: Add 8.0g of m-phenylenediamine, spherical alumina, silicone defoamer and silicone leveling agent to the mixed components, and disperse at high speed for 35 min at 25℃ and 2500rpm.

[0054] Step 3: Vacuum degassing at 25℃ and -0.1MPa for 25 minutes.

[0055] Example 4

[0056] A one-component silicone-modified heat-resistant epoxy structural adhesive composition is prepared by the following steps:

[0057] Step 1: Mix the 21.0g phenolic epoxy resin, 21.25g bisphenol F type epoxy resin, 26.90g epoxy modified silicone oil, 21.3g methyl phenyl silicone resin containing alkoxy functional groups, and 24.1g amino phenyl silicone oil according to the weight parts, and stir at high speed at 25℃ and 1500rpm for 25min.

[0058] Step 2: Add 8.0 parts of m-phenylenediamine, 63.0 g of spherical alumina, 2.9 g of silicone defoamer and 2.9 g of silicone leveling agent to the mixed components, and disperse at high speed for 40 min at 25℃ and 2500 rpm.

[0059] Step 3: Vacuum degassing at 25℃ and -0.1MPa for 35 minutes.

[0060] Example 5

[0061] A one-component silicone-modified heat-resistant epoxy structural adhesive composition is prepared by the following steps:

[0062] Step 1: Mix the 21.00 g phenolic epoxy resin, 21.25 g bisphenol F type epoxy resin, 26.9 g epoxy modified silicone oil, 22.6 g methyl phenyl silicone resin containing alkoxy functional groups, and 30.1 g amino phenyl silicone oil according to the weight parts, and stir at high speed at 25°C and 1300 rpm for 20 min.

[0063] Step 2: Add 6.0g of dicyandiamide, 63.0g of spherical alumina, 3.0g of silicone defoamer and 3.0g of silicone leveling agent to the mixed components, and disperse at high speed for 35 min at 25℃ and 2500rpm.

[0064] Step 3: Vacuum degassing at 25℃ and -0.1MPa for 20 minutes.

[0065] Comparative Example 1

[0066] A one-component silicone-modified heat-resistant epoxy structural adhesive composition is prepared by the following steps:

[0067] Step 1: Mix 20.0g of phenolic epoxy resin, 20.4g of bisphenol F type epoxy resin, 70.8g of epoxy modified silicone oil and 28.0g of methyl phenyl silicone resin containing alkoxy functional groups according to the weight parts, and stir at high speed at 25℃ and 1500rpm for 20 min.

[0068] Step 2: Add 8.0g of dicyandiamide, 73.0g of spherical alumina, 3.2g of silicone defoamer and 3.2g of silicone leveling agent to the mixed components, and disperse at high speed for 30 min at 25℃ and 2500rpm.

[0069] Step 3: Vacuum degassing at 25℃ and -0.1MPa for 20 minutes.

[0070] Comparative Example 2

[0071] A one-component silicone-modified heat-resistant epoxy structural adhesive composition is prepared by the following steps:

[0072] Step 1: Mix 20.0g of phenolic epoxy resin, 20.4g of bisphenol F type epoxy resin, 28.0g of methyl phenyl silicone resin containing alkoxy functional groups and 70.8g of aminophenyl silicone oil according to the weight parts, and stir at high speed at 25℃ and 1500rpm for 20 min.

[0073] Step 2: Add 8.0g of dicyandiamide, 65.0g of thermally conductive powder, 3.3g of silicone defoamer and 3.3g of silicone leveling agent to the mixed components, and disperse at high speed for 30 min at 25℃ and 2500rpm.

[0074] Step 3: Vacuum degassing at 25℃ and -0.1MPa for 20 minutes.

[0075] Comparative Example 3

[0076] A one-component epoxy structural adhesive composition is prepared by the following steps:

[0077] Step 1: Mix the 36.6g phenolic epoxy resin, 76.7g bisphenol F type epoxy resin, and 25.9g methylphenyl silicone resin containing alkoxy functional groups, and stir at high speed at 25℃ and 1500rpm for 20 minutes.

[0078] Step 2: Add 8.0g of dicyandiamide, 73.0g of spherical alumina, 3.2g of silicone defoamer and 3.2g of silicone leveling agent to the mixed components, and disperse at high speed for 30 min at 25℃ and 2500rpm.

[0079] Step 3: Vacuum degassing at 25℃ and -0.1MPa for 20 minutes.

[0080] Performance testing

[0081] I. Testing Standards:

[0082] 1. Viscosity test: In accordance with GB / T 2794-2022 standard, the viscosity of the examples and comparative examples was tested using a rotating viscometer under standard conditions (temperature 23±2℃, humidity 50±5%).

[0083] 2. Density test: Tested according to GB / T6750-2007.

[0084] 3. Coating sample standard: Use a No. 1 electrolytic pure copper plate with a thickness of 0.4 mm and a surface polished with sandpaper as the substrate, and apply a 150 μm thick structural adhesive to the surface of the copper plate; the curing temperature is 180℃ and the curing time is 20 min.

[0085] 4. Insulation test: Determine the DC and AC withstand voltage strength of the sample according to GB / T 1408 standard.

[0086] 5. Flexibility Test: Bend the pure copper plate with the adhesive layer 90° in both directions with an inner radius of R5. Observe the condition of the adhesive surface at the bending point to see if it is intact, and check for any cracks or peeling. Measure the AC / DC withstand voltage at the bending point according to the insulation test standard.

[0087] 6. Pull-out force test: A pure copper metal fixture with a cross-sectional diameter of 1.5 cm is used. Glue is applied to the cross-section and cured at the temperature and time specified in the sheet preparation standard. The maximum pull-out force is then tested using a tensile testing machine at a speed of 200 mm / min.

[0088] 7. Adhesion test: The adhesion of the adhesive surface shall be determined by an adhesion tester in accordance with GB / T 9286-1998.

[0089] High and low temperature impact test: One high and low temperature cycle is defined as placing the sample at -30℃ for 15 minutes and at 290℃ for 15 minutes. The sample is placed in this environment for 3, 6 and 12 cycles respectively. After the cycle, the insulation, flexibility, pull-out force and adhesion of the sample are measured.

[0090] Result detection characterization

[0091] 1. Technical parameter characterization

[0092] Table 1 Physical properties of Examples 1-5 and Comparative Examples 1-3

[0093] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Viscosity / cp 4231 5728 3900 5412 4987 6650 6234 7234 <![CDATA[Density / g·cm -1 > 1.14 1.85 1.32 1.68 1.50 1.53 1.28 1.47

[0094] 2. Adhesion test results

[0095] Table 2 Adhesion test results of Examples 1-5 and Comparative Examples 1-3

[0096]

[0097] As can be seen from Table 2, the single-component silicone-modified high-temperature resistant epoxy structural adhesive composition provided in this application has an adhesion grade of ≤1 after 12 high and low temperature cycles (-55℃↔150℃); and further verification revealed that the edge lifting area of ​​Examples 1-5 was <3%.

[0098] According to the results of Comparative Example 1, in the absence of aminophenyl silicone oil, interface whitening and ≥2-level adhesion failure occurred after 3 cycles. The possible reason is that aminophenyl silicone oil reacts with the substrate and epoxy resin through its primary amino group (-NH2) to form a dense bonding layer at the interface, which inhibits phase separation. In Examples 1-5, the addition of aminophenyl silicone oil prevented interface whitening after thermal cycling.

[0099] According to the results of Comparative Example 2, in the absence of epoxy-modified silicone oil, radial cracks appeared after 6 cycles, resulting in failure of ≥4 level. It is speculated that the reason is that epoxy-modified silicone oil can absorb thermal stress through flexible segments and prevent brittle fracture. Therefore, this application can maintain good adhesion after high and low temperature impact when epoxy-modified silicone oil is added.

[0100] When both types of silicone oil are missing, Comparative Example 3 delaminated after 3 cycles and completely pulverized after 12 cycles; it can be inferred that aminophenyl silicone oil and epoxy-modified silicone oil have a synergistic effect, which can synergistically improve the adhesion retention of the composition after high and low temperature impact.

[0101] Furthermore, based on Examples 1-5, it can be inferred that when the content of aminophenyl silicone oil is ≥20 parts, it prevents interface degradation, and when the content of epoxy modified silicone oil is ≥25 parts, it maintains the integrity of the bulk phase. The combined effect of the two makes the adhesion stable at ≤1 level after 12 cycles, which is significantly better than Comparative Examples 1-3 which lack either component (the degradation rate is accelerated by more than 300% after 3 cycles).

[0102] 3. Insulation test results

[0103] Tables 3 and 4 show the DC and AC insulation test results of Examples 1 to 5 and Comparative Examples 1 to 3.

[0104] Table 3. DC test results of Examples 1-5 and Comparative Examples 1-3

[0105]

[0106] Table 4. AC test results of Examples 1-5 and Comparative Examples 1-3

[0107] According to the data in Tables 3 and 4:

[0108] Examples 1-5 of this application exhibit excellent insulation performance retention after thermal shock. At 0 cycles, the DC breakdown strength of Examples 1-5 ranges from 2.93 to 3.12 kV, and the AC breakdown strength ranges from 2.96 to 3.11 kV. After 12 cycles, the DC breakdown strength remains between 2.31 and 2.78 kV, and the AC breakdown strength remains between 2.03 and 2.59 kV. Example 2 exhibited the best performance retention, with its DC breakdown strength decreasing from an initial 2.98 kV to 2.78 kV (retention rate 93.3%) and AC breakdown strength decreasing from 3.05 kV to 2.59 kV (retention rate 84.9%). In contrast, Example 3 maintained an AC breakdown strength of 2.03 kV after 12 cycles. Analysis revealed that this stable electrical insulation performance was attributed to the effective suppression of air gap discharge by the dense molecular layer formed at the interface by the aminophenyl silicone oil, while the flexible segments of the epoxy-modified silicone oil absorbed thermal stress to prevent the formation of microcracks, thus jointly maintaining the bulk insulation integrity.

[0109] The comparative examples showed severe performance degradation. Comparative Example 1's DC breakdown strength dropped sharply from 3.09 kV to 1.58 kV after 3 cycles (a decrease of 48.9%), and further decreased to 0.41 kV after 12 cycles (a cumulative decrease of 86.7%). Comparative Example 2's DC breakdown strength decreased from 2.95 kV to 0.62 kV after 6 cycles (a decrease of 79.0%), and the AC breakdown strength was only 0.11 kV after 12 cycles (a decrease of 96.3%). Comparative Example 3's DC breakdown strength dropped to 0.82 kV after 3 cycles (a decrease of 72.8%), and completely failed to 0.12 kV after 12 cycles. It is speculated that the sharp decline may be due to the following reasons: the lack of aminophenyl silicone oil caused the aggregation of interfacial micropores, leading to early electrical breakdown; the lack of epoxy modified silicone oil caused the propagation of bulk cracks; and the synergistic loss of both resulted in the complete loss of insulation function.

[0110] Data analysis shows that the technical solution in this embodiment exhibits a DC breakdown strength attenuation rate of ≤0.05 kV / cycle after 12 cycles (average of 0.046 kV / cycle for Examples 1-5), significantly outperforming Comparative Examples 1-3 (attenuation rate ≥0.22 kV / cycle). Particularly noteworthy is the performance at the critical 3-cycle mark, where the embodiment maintains a DC breakdown strength ≥2.87 kV (average 2.93 kV), while the comparative examples all maintain ≤1.58 kV (average 1.28 kV), a performance difference of 2.3 times. This significant difference cannot be compensated for by conventional component adjustments, demonstrating the irreplaceable crucial role of the synergistic effect of the two silicone oils in maintaining electrical insulation reliability under extreme temperature alternation environments.

[0111] Tables 5 and 6 show the DC test results of the 90-degree bending flexibility test for Examples 1-5 and Comparative Examples 1-3.

[0112] Table 5. DC test results of the flexibility test at 90 degrees bending in Examples 1-5 and Comparative Examples 1-3.

[0113]

[0114] Table 6. AC test results of flexibility tests at 90 degrees bending in Examples 1-5 and Comparative Examples 1-3.

[0115] According to the data in Tables 5 and 6:

[0116] Examples 1-5 of this application maintained high insulation performance even after being bent 90° following thermal shock. After zero impact bends, the DC withstand voltage of Examples 1-5 ranged from 1.87-2.15kV (mean 1.99kV), and the AC withstand voltage ranged from 1.72-2.03kV (mean 1.86kV). After 12 impact bends, the DC withstand voltage remained at 1.27-1.78kV (mean 1.47kV), and the AC withstand voltage remained at 1.22-1.71kV (mean 1.42kV). Example 2 showed the best performance, with a DC withstand voltage of 1.78kV (retention rate 82.8%) and an AC withstand voltage of 1.71kV (retention rate 84.2%) after 12 impact bends. This was attributed to the effective suppression of bending microcrack propagation by the flexible segments of the epoxy-modified silicone oil. In Example 3, the AC withstand voltage still reached 1.22kV after 12 impact bends, demonstrating the resistance of the phenyl structure to bending stress.

[0117] Comparative Examples 1-3 exhibited severe insulation failure under bending conditions. In Comparative Example 1, after 13 impact bends, the DC withstand voltage plummeted from 1.85kV to 0.65kV (a decrease of 64.9%), and after 12 bends, only 0.14kV remained (a decrease of 92.4%). In Comparative Example 2, after 6 impact bends, the AC withstand voltage decreased from 1.72kV to 0.18kV (a decrease of 89.5%). In Comparative Example 3, after 3 impact bends, the DC withstand voltage had dropped to 0.31kV (a decrease of 83.8%). It is speculated that this discontinuous attenuation stems from the absence of aminophenyl silicone oil, leading to microporous chains at the bending interface, and the absence of epoxy-modified silicone oil, resulting in bending crack lengths exceeding 500μm. The combined absence of these two factors causes pulverized fracture of the insulation layer after bending.

[0118] The technical solution of this application maintains a DC withstand voltage retention rate of ≥63.4% after 12 thermal shock bends (72.2% in Example 1), while the retention rate of the comparative example is ≤7.6%. In particular, at the critical point of 6 impact bends, the average AC withstand voltage of the example is 1.60kV (minimum 1.43kV), while the average value of the comparative example is only 0.19kV, with a performance difference of 8.4 times. Analysis suggests that the reason for this magnitude difference may be that the two silicone oils play an irreplaceable core role in maintaining the electrical insulation reliability under bending conditions through the synergistic mechanism of interfacial bonding (preventing micropores) and bulk toughening (inhibiting cracks).

[0119] 4. Pull-out force test

[0120] Table 7 shows the pull-out force test results for Examples 1-5 and Comparative Examples 1-3.

[0121] Table 7 Pull-out force test results of Examples 1-5 and Comparative Examples 1-3

[0122]

[0123] According to the data in Table 7, we can see that...

[0124] Examples 1-5 of this application maintain excellent bond strength after thermal shock; at 0 impacts, the pull-out force of Examples 1-5 is between 21.84-23.17 MPa (average 22.28 MPa); after 12 impacts, the pull-out force remains at 18.25-21.08 MPa (average 19.44 MPa), with a retention rate of over 86.0%.

[0125] Example 2 showed the best performance, with a pull-out force of 21.08 MPa after 12 impacts (retention rate of 91.0%). This was due to the effective buffering of thermal stress by the flexible segments of the epoxy-modified silicone oil, which suppressed interface debonding. Example 3 maintained 18.25 MPa after 12 impacts (retention rate of 83.5%), proving that the phenyl structure enhances the interface anchoring effect.

[0126] In Comparative Example 1, the pull-out force dropped sharply from 21.92 MPa to 14.27 MPa after 13 impacts (a decrease of 34.9%), and collapsed to 4.25 MPa after 12 impacts (a cumulative decrease of 80.6%). In Comparative Example 2, the strength decreased from 21.57 MPa to 6.42 MPa after 26 impacts (a decrease of 70.2%). In Comparative Example 3, the strength dropped to 9.46 MPa after 3 impacts (a decrease of 57.3%), and was reduced to only 1.08 MPa after 12 impacts (a decrease of 95.1%). This precipitous decline may be due to the following reasons: the lack of aminophenyl silicone oil leads to interfacial bonding failure, and the lack of epoxy modified silicone oil causes colloid embrittlement (elongation at break <10%). The synergistic loss of both results in the complete loss of adhesive function.

[0127] The technical solution of this application maintains a pull-out force retention rate of ≥83.5% after 12 thermal shocks (Example 3), while the retention rate of the comparative examples is ≤19.4%. Particularly at the critical point of the third shock, the average pull-out force of Examples 1-5 is 21.56 MPa (minimum 20.93 MPa), while the average of Comparative Examples 1-3 is only 12.19 MPa (maximum 14.27 MPa), a performance difference of 1.8 times. After 12 shocks, the difference widens to 4.6 times (Example 19.44 MPa / Comparative Example 4.25 MPa). This magnitude difference may be due to the synergistic effect of aminophenyl silicone oil and epoxy-modified silicone oil through interfacial chemical bonding and bulk force buffering, which plays a decisive role in maintaining the structural bonding reliability under extreme temperature alternation environments.

[0128] The embodiments presented herein are merely selected implementations based on combinations of all possible embodiments. The appended claims should not be limited to the embodiments described herein. Some numerical ranges used in the claims include sub-ranges within them, and variations within these ranges should also be covered by the appended claims.

Claims

1. A one-component organosilicon-modified high-temperature resistant epoxy structural adhesive composition, characterized in that, By weight, it includes: 40-75 parts epoxy resin, 26-47 parts epoxy modified silicone oil, 21-28 parts methyl phenyl silicone resin containing alkoxy functional groups, 6-8 parts curing agent, 24-40 parts amino phenyl silicone oil, 0-18 parts defoamer, and 1-3 parts leveling agent. The side chain or end chain of the epoxy-modified silicone oil contains at least one epoxy group; The aminophenyl silicone oil has an amino equivalent of 670-3750 g / eq and a phenyl content of 0.10-0.40 mol / 100g.

2. The single-component organosilicon-modified high-temperature resistant epoxy structural adhesive composition according to claim 1, characterized in that, The epoxy resin comprises 20-35 parts of phenolic epoxy resin and 20-25 parts of bisphenol F type epoxy resin; the epoxy equivalent of the phenolic epoxy resin should be between 92-110 g / eq, and the epoxy equivalent of the bisphenol F type resin should be between 160-500 g / eq.

3. The single-component organosilicon-modified high-temperature resistant epoxy structural adhesive composition according to claim 1, characterized in that, The epoxy group of the epoxy-modified silicone oil is at least one of glycidyl ether, epoxycyclohexyl, oxetyl, and tetrahydrofuran.

4. The single-component organosilicon-modified high-temperature resistant epoxy structural adhesive composition according to claim 1, characterized in that, The alkoxy-containing functional group includes at least one of methoxy, ethoxy, propoxy, and isopropoxy.

5. The single-component organosilicon-modified high-temperature resistant epoxy structural adhesive composition according to claim 4, characterized in that, The alkoxy-containing functional group is directly connected to silicon atoms to form a Si-R structure, where R is an alkoxy-containing functional group.

6. The single-component organosilicon-modified high-temperature resistant epoxy structural adhesive composition according to claim 1, characterized in that, The curing agent is at least one of divinyltriamine, dicyandiamide, diaminodiphenylmethane, adipate dihydrazide, m-phenylenediamine, m-phenylenediamine, and isophorone diamine.

7. The single-component organosilicon-modified high-temperature resistant epoxy structural adhesive composition according to claim 1, characterized in that, It also includes thermally conductive powder, the content of which in the single-component silicone-modified high-temperature resistant epoxy structural adhesive composition is 40-45 wt%.

8. The method for preparing the single-component organosilicon-modified heat-resistant epoxy structural adhesive composition according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Mix epoxy resin, epoxy modified silicone oil, methyl phenyl silicone resin containing alkoxy functional groups and amino phenyl silicone oil evenly to obtain a mixture; Step 2: Add curing agent, defoamer and leveling agent to the mixture and disperse to obtain a dispersion; Step 3: Vacuum degassing at 25℃ and -0.1MPa for 15-30 min to obtain the composition.

9. The method for preparing the single-component organosilicon-modified heat-resistant epoxy structural adhesive composition according to claim 7, characterized in that, Includes the following steps: Step 1: Mix epoxy resin, epoxy modified silicone oil, methyl phenyl silicone resin containing alkoxy functional groups and amino phenyl silicone oil evenly to obtain a mixture; Step 2: Add curing agent, defoamer, thermally conductive powder and leveling agent to the mixture and disperse to obtain a dispersion; Step 3: Vacuum degassing at 25℃ and -0.1MPa for 15-30 min to obtain the composition.

10. The method for preparing the single-component organosilicon-modified heat-resistant epoxy structural adhesive composition according to claim 8 or 9, characterized in that, The mixing method in step 1 is as follows: high-speed stirring and mixing at 25℃ and 1200-1500 rpm for 20-25 min; the dispersion method in step 2 is as follows: high-speed dispersion at 25℃ and 2500 rpm for 30-40 min.

Images